The Heart 1 of 34 Boardworks Ltd 2012
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What does the heart do? 3 of 34 Boardworks Ltd 2012 The heart is a muscular organ located in the thorax. It pumps blood continuously around the body. The blood supplies cells with oxygen and glucose, needed for respiration. The blood also transports the waste products, such as carbon dioxide, the waste product of respiration, and urea. Special arteries called coronary arteries carry blood to the heart to supply the heart muscle cells with oxygen and glucose for contraction.
Circulatory systems 4 of 34 Boardworks Ltd 2012 A circulatory system consists of a group of organs that transport substances, such as oxygen, around the body. heart Some organisms, such as insects, have an open circulatory system, where the fluid moves freely between cells. Other organisms, including humans, have a closed circulatory system where blood is contained within vessels, where these factors can be controlled: the speed of blood flow the pressure of the blood the distribution of blood in the body.
One and two circuits 5 of 34 Boardworks Ltd 2012
Closed circulatory systems 6 of 34 Boardworks Ltd 2012 A single circulatory system has a two-chambered heart so that blood can be returned to one chamber, and pumped back out of the heart from the second chamber. This ensures blood flow in one direction only. The double circulatory system has a four-chambered heart so that blood can be pumped out to the lungs, returned to the heart, and be pumped out again to the rest of the body. This maintains a high pressure in the blood vessels and faster blood flow to the tissues. This is essential for organisms with a large body, such as whales, elephants, and humans.
Structures of the heart 7 of 34 Boardworks Ltd 2012
Contraction and relaxation 8 of 34 Boardworks Ltd 2012
Which structure? 9 of 34 Boardworks Ltd 2012
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Electrical activity 11 of 34 Boardworks Ltd 2012
What is an electrocardiogram? 12 of 34 Boardworks Ltd 2012 The electrical activity of the heart can be monitored by using an electrocardiograph. Several electrodes are attached to specific places on a person s chest. These detect electrical changes in the heart by measuring current at the skin s surface. The leads are connected to a machine that draws an electrocardiogram (ECG). A normal ECG is shown below.
Showing electrical activity 13 of 34 Boardworks Ltd 2012
Components of an ECG trace 14 of 34 Boardworks Ltd 2012
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Heart rate and exercise 16 of 34 Boardworks Ltd 2012 During exercise several changes occur: the heart rate increases the rate and depth of breathing increases the arteries supplying the muscles dilate. These changes help to provide oxygen and glucose to muscles and remove carbon dioxide more quickly. Heart rate can also be altered by hormones such as adrenaline. The presence of adrenaline causes the heart rate to increase, allowing a quick response to danger.
How does regular exercise affect the heart? 17 of 34 Boardworks Ltd 2012 Regular exercise can strengthen the heart, causing: the heart to become bigger the amount of blood pumped by the heart to increase the walls of the heart to become thicker and stronger. The result is that the heart becomes a more efficient pump. The resting pulse rate gets slower as a person becomes fitter, because the heart needs fewer beats to pump blood round the body.
Pulse rate graph 18 of 34 Boardworks Ltd 2012
Heart rate during exercise 19 of 34 Boardworks Ltd 2012
Interpret the data 20 of 34 Boardworks Ltd 2012
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Heart problems: introduction 22 of 34 Boardworks Ltd 2012
Heart disease and BMI 23 of 34 Boardworks Ltd 2012 Obese people have a higher risk of developing heart disease. An individual s body mass index, or BMI, can indicate whether they are obese. BMI measures the relative amounts of fat and muscle in the body. Gloria: Zak: 1.45m and 66kg BMI = 31 1.85m and 66kg BMI = 19 BMI = body mass (kg) (height) 2 (m) BMI <20 20 25 25 30 >30 Conclusion underweight normal overweight obese Use the table to see who has a greater risk of developing heart disease.
BMI calculations 24 of 34 Boardworks Ltd 2012
ECG in diagnosis of irregular heartbeats 25 of 34 Boardworks Ltd 2012 ECGs are used to diagnose problems with the heart, as variations in different components of the trace can indicate a disease or other abnormality. An ECG may be taken while the patient is relaxed or it may be taken before, during and after exercise. This is called a stress test and usually involves the patient exercising on a treadmill while attached to an ECG machine.
Irregular heartbeats 26 of 34 Boardworks Ltd 2012
Diagnosing heart problems 27 of 34 Boardworks Ltd 2012 An echocardiogram is a diagnostic test that uses sound waves which echo against structures to build up a detailed picture of the heart. A transducer is placed on the chest of the patient. This emits sound waves and detects the reflected echoes. Doctors use this test to help diagnose heart problems such as coronary heart disease, weak valves and heart defects, such as a hole in the heart.
28 of 34 Boardworks Ltd 2012 Hole in the heart A hole in the heart describes an opening in the wall of the heart that separates the right side from the left. As deoxygenated blood is now able to mix with oxygenated blood, the amount of oxygen being carried to respiring tissues is less. Unborn babies all have a hole in their hearts to allow blood flow between the ventricles. As the lungs are not used in the womb, this hole diverts blood flow away from the pulmonary circulation. This hole closes after birth when the lungs are needed for gas exchange.
Heart assist device: pacemaker 29 of 34 Boardworks Ltd 2012 Some heart problems are caused by an impairment of the natural pacemaker cells in the heart. This can be treated by installing an artificial pacemaker. This battery-powered device monitors the heart s electrical activity and stimulates the ventricles or atria to contract at the right time. Impulses are transmitted down electrodes implanted in the heart s muscular walls. A pacemaker can be installed using simple surgery. This can be a simpler and safer alternative to replacing the natural pacemaker cells by undergoing a heart transplant.
Biomedical engineering 30 of 34 Boardworks Ltd 2012 Scientists must understand how the heart functions normally so they can design suitable solutions for those with heart conditions and diseases. Examples include the biomedical engineering of: artificial pacemakers to control the heart beat replacement devices for faulty heart valves artificial hearts to use in heart transplants. What are the advantages and disadvantages of a heart pacemaker or artificial heart valves over a heart transplant?
Evaluate 31 of 34 Boardworks Ltd 2012
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Glossary 33 of 34 Boardworks Ltd 2012
Multiple-choice quiz 34 of 34 Boardworks Ltd 2012